1. Field of the Invention
The present invention relates to a turbocharger in which multiple pressure receiving portions provided in a thrust bearing receives a thrust load.
2. Description of the Related Art
A conventional turbocharger includes a turbine shaft whose ends are provided with turbine and compressor wheels (impellers), respectively. The turbine shaft is rotatably supported by a bearing housing. Such a turbocharger is connected to an engine. An exhaust gas discharged from the engine rotates the turbine wheel, and the rotation of the turbine wheel rotates the compressor wheel through the turbine shaft. The rotation of the compressor wheel compresses the air, and the compressed air is supplied to the engine.
A thrust bearing is placed opposite a thrust collar provided to the turbine shaft with the turbine shaft inserted in an insertion hole of the thrust bearing. The thrust bearing receives a load in the axial direction of the turbine shaft (thrust load) which acts on the turbine shaft. An opposed surface of the thrust bearing which is opposite the thrust collar is provided with multiple pressure receiving portions arranged in the circumferential direction of the turbine shaft, and each projecting from the opposed surface toward the thrust collar. Each pressure receiving portion forms an oil film between the pressure receiving portion and the thrust collar, and receives the thrust load by use of oil film pressure. After lubricating and cooling the thrust bearing, the lubricant is discharged via a discharge port or a cutout which is formed vertically below the insertion hole of the thrust bearing. A turbocharger described in Japanese Patent Application Laid-Open Publication No. 2010-121589 (Patent Document 1) is provided with a through-hole which penetrates through the thrust bearing from the insertion hole to the discharge port, and is thus configured to improve a performance to discharge a lubricant.